1-158-478 - Oxford Science Archive/Heritage Images

Athanor or 'Slow Harry', a self-feeding furnace maintaining a constant temperature, 1683. Centre: 1) Athanor or 'Slow Harry'; 2) side chambers containing reagents; 3) glass receivers. Back: 5) furnace heating retort. Bottom: 7) long furnace. This plate shows the distillation of nitirc acid (also known as Aqua Fortis or Parting Acid) which was used in the refining and assaying of metals. From a 1683 English edition of Beschreibung allerfurnemisten mineralischen Ertzt by Lazarus Ercker. (Prague, 1574).